MVVM anti-pattern: Injecting the IoC container into a View Model

This is another anti-pattern I've seen a lot recently, the dynamic use of the IoC container inside a view model to resolve child view models & services - service locator pattern: The service locator pattern has been around for a while - Fowler was writing about this back in 2004!It's not a pattern that is specific to MVVM, it's a pattern associated with using DI & IoC, if you're doing MVVM you should be using DI & IoC. A lot has also...

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MVVM anti-pattern: View code behind with no implementation

I've seen rather a lot of this anti-pattern recently, to be explicit about what I mean, lets define this in terms of a WPF user control. Imagine the code behind file is nothing more than the auto generated code, but the XAML file contains the usual controls and bindings:The user control is used in one or more data templates as follows:The reason this is an anti-pattern is because it has introduced files into the solution which aren't required: The...

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MVVM anti-pattern: explicitly using data context in View code behind

I believe explicitly using the data context in the code behind of the view (custom, user control etc) in any MVVM application is an anti-pattern. The view has no need to explicitly access the data context it is there purely for binding concerns. The following screen shot illustrates what I mean:This is an anti-pattern because the view knows about the view model - as you can see the data context is being cast to the DataContextViewModel. The view...

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Implementing a message box using a visual overlay in MVVM

I've blogged about implementing a busy indicator before, this post is an extension of this pattern to implement a message box - this is instead of using the namespace provide by the .Net framework.The UI is shown below, and when the button is clicked in the middle content it will display the message as an overlay - as you can see I've coloured it green to get your attention:As with the previous post, the XAML for the View hasn't changed it's still...

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Using IoC nested lifetime scopes with View Models in MVVM

A common pattern you see when developing web services is the use of the Unit of Work applied to the HTTP request - anything that happens during the processing of the request is viewed as being part of the transaction and therefore when the request is completed any memory allocated during the processing of the request can be garbage collected.  Whether the request is successfully or not is irrelevant in this context the important concept is the...

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Integration tests written in .Net using locally hosted node.js server

I've blogged before about hosting web services created with Web API inside a test fixture in .Net, what follows is the same idea but in this case hosting a node.js implemented web service, this is using the node.js server I created in this previous post.Jumping straight to the solution this is what I came up with:As you can I've managed to reduce the amount required to be specified for each test fixture to 3 parameters:working directory for node.js...

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Building mock web service in node.js instead of Web API

I needed to build a mock back-end web service this week because the middle-ware team wasn't ready (they're useless standard Java 'enterprise' developers) and @Jason challenged me to write it in node.js. He showed me an example of how this was done before and said it shouldn't take more than 5 minutes to have something up and running, I've done this kind of requirement previously in Web API and thought it would be interesting to finally do 'something'...

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Suspending & resuming property notifications when using INotifyPropertyChanged

Currently I'm working with some UI code which has a 'domino effect' when a property changes on a view model - the data is being rendered in a tree view, and the reason for the 'domino effect' is because the value of a node in the tree view is an aggregation of multiple child nodes (leaf nodes hold the actual values which are aggregated up). The dataset is dynamic, it can be updated during it's visualization and when this happens we want the ability...

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Daily Dilbert Service - the most important service I've ever written...

NuGet package available here...First off a big shout to @hamish & @leeoades on this one - I'm just blogging about it. At work we have a test harness for launching the application in different environments, the test harness like the app is written in WPF. We got very bored of looking at the test harness UI and decided to make it a bit more interesting - we added the Daily Dilbert comic strip to the button to launch the app...

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Testing when the culture changes in WPF

Recently I've do some work on a WPF app which required to support multiple languages in the UI - a spike to see how easy supporting multiple languages is in WPF, the test UI is shown below in English & French:The app is easy enough to understand - change the UI language and all the text based values are updated with the locale specific instances. I wanted to follow the standard pattern of using language specific resource files to store the translated...

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